Flaw detector mechanism



Nov. 23, 1937. c, DRAKE FLAW [DETECTOR MECHANISM Filed Nov. 17, 1933 3 nveutor fizwcaupr C DAM/(E 3g WKW? ttorneg Patented Nov. 23, 1937 UNITED STATES PATENT OFFICE FLAW DETECTOR LIECHANISM Harcourt C. Drake, Hempstead, N. Y., assignorto Sperry Products, Inc., Brooklyn, N. Y., a corporation of New York Application November 17, 1933, Serial No. 698,399

4 Claims. (01. 177-311 of induction coils designed to induce an E. M. F.- 10 whenever an irregularity in the electromagnetic field is encountered.

The present invention has for its principal object the provision of means whereby an operator can at all times know whether the detector [5 mechanism is functioning.

Further objects and advantages of my invention will become apparent in the following detailed description thereof.

In the accompanying drawing,

30 Fig. 1 is a side elevation of a portion of a Sperry rail flaw detector car.

Fig. 2 is a wiring diagram embodying my invention.

Referring to the drawing, there is disclosed a 35 portion of a Sperry rail fiaw detector car comprising the car body ill within which is mounted-a generator G adapted to supply current to the rail to establish an electromagnetic field surrounding the same. The current from generator G may be'passed into and out of the rail by means of sets of brushes II and I2 carried by a current brush carriage l5, said carriage being supported from the car body ID by means such as cables 16 and springs, not shown, which normally maintain the current brush carriage in raised or inefiective position. When it is desired to lower such carriage into engagement with the rail, fluid pressure, such as compressed air, is supplied to cylinders I! to depress pistons 18 operating therein, said pistons being connected to the current brush carriage so that said carriage is lowered against the action of the rectractile springs. The current brush carriage may be adapted to ride along the rail on means such as flange-d wheels l9.

-5 The electromagnetic field surrounding the rail is uniform as long as there are no flaws. When flaws occur there is a distortion of the electromagnetic field in the region of the flaw and such distortions are designed to be detected by induction means which in the present case comprise a pair of opposed induction coils 20 supported in a housing 2|, carried by a detector carriage 22 which is designed to be supported on the current brush carriage for movement independent thereof by means such as loose-fitting bolts 23 and springs 24 constituting limited universal joints. The detector carriage 22 may be supported on the rail surface by means such as rollers 25. It will now be seen that as the car travels along the rail R the inductive means 20 5 are maintained a constant distance above the rail surface and will normallycut a constant number of lines of force. When a region of flaw is encountered one of the coils will cut a difierent number of lines of force and there will be generated a difierential E. M. P. which after being amplified by an amplifier A may be caused to operate indicating means such as pens operating on a moving'chart.

The output of amplifier A is caused to energize a plurality of relays 30, 3! of varying degrees of strength so that a region of weak flaw will energize, for example, only relay 30, while a region of considerable flaw will energize relays 38 and 3|. The energization of said relays is causedto operate pens P and P, respectively, by attracting armatures 30" and 3 l to close contacts 32 and 33 which will energize pen magnets 34 and 35 to attract the pens P, P. Said pens normally trace straight lines along a-moving chart but when the magnets 34, 35 are energized the pens are attracted out of their normal path to make a jog in the line and thus indicate the presence of a flaw.

Since every rail joint will distort the electromagnetic field to a very marked degree, the detector mechanism hereinbefore described would pick up every rail joint and cause the pens P and P to be actuatedw'several times in passing over each rail joint to give an indication as of a prolonged region of flaw. This is due to the fact that at each joint there are angle bars of con- 7 siderable length, bolts, etc., all of which tend to distort the normal axis of the current. There is therefore provided means for cutting out the indications of pens P and P when a joint is 40' reached. For this purpose, there are provided joint fingers 40 and ll in advance of the detector mechanism and to the rear of it. These joint fingers are adaptedto engage the side of the rail head so that they will engage the projecting part of the angle bar when a joint is reached, and they are so positioned that the rearfinger will engage the angle bar before the forward finger has passed beyond it. Therefore, one or the other of fingers 40, M will be in engagement with said angle bar throughout the entire period that the detector mechanism 20 is passing over said angle bar. The engagement of joint fingers 40, 4| with the angle bar is caused to break thecircuit to thepen relays 34, 35103! reason of the fact that said fingers are pivoted at 40, 4| and have means beyond said pivot for closing contacts 42, 43 which are arranged in parallel so that closing of either set of contacts 42, 43 will energize a relay 45 to attract an armature 46 and break contacts 41 which are in the circuit leading from output relays and 3| to the pen relays 34 and 35. Thus, although relays 30 and 3| are energized by reason of the detector coils passing over the joint, the pens P and P are not actuated.

. At the same time that relay 45 is energized a relay 48 is also energized by the closing of contacts 42 or 43, to attract an armature 49 and close the set of contacts 53 to energize a joint pen relay 5| designed to operate a joint pen J. Said pen also traces a straight line normally on the chart, but when relay 5| is energized by the joint cutout fingers 45 and 4| the pen is attracted to make a jog in the line and thus indicate the presence of a flaw. As soon asthe joint is passed over, that is, as scenes the rear joint cutout finger 4| hasbeyondthe angle bar,relays 45 and 43 are de-energized to close contacts 41 and thus render pen magnets 34 and 33 again effective to respond to impulses transmitted theretobyoutput relays and3| andthusperinitpensPandP'tooperateagain. Atthesame time contacts 53 open and thejoint pen J is returned to its normal indicating position.

It may occur that for some reason, such as broken connections, short circuits and the like, the detector system originating with the induction coils 24 and extending by means of electrlcal connections into the amplifier and thence to the output relays 39 and 3|, may be inopera- ,tive and may not be functioning. It is very difilcult to detect such a condition ordinarily because the pens P and P function only when a flaw comes through, and if the detector system has broken down, pens P and P will simply make a straight line record showing no fiaws and the operator will merely consider that the track traversed is without internal fissures, whereas in fact the detector system is not functioning at all. In order to have some indication as to whether or not the detector system is functioning I utiline that interval during which the pen relays 34 and are actuated by the joint cutout mechanism described above. That is to say, when the contacts 41 are opened to break the pen relay circuits 34, 35, I provide means for operating a circuit from the output of the amplifier and place within that circuit some suitable signal.

In order to accomplish the above object, I-provide in the output of the amplifier an additional output relay 29 of lesser strength than either relay 39 or 3| so that any output which would be sufilcient to actuate the output relays 39 and 3| and hence the relay pens 34 and 35 will be sufficient to energize relay 29. I cause said relay 29 when energized to attract an armature 29' to close contacts 59 which will close a circuit in parallel with joint pen relay 5| (since the joint pen relay circuit is operative during this interval), in which circuit I place a suitable signal 6| which may be a light, as shown or a sound signal or any other suitable indicator; The shunt circuit begins at points 62 and 63 and includes the leads 54, 65.. The effect of this construction is that when contacts 50 are closed by the joint cutout mechanism hereinbefore described to close the circuit through joint pen relay 5|, relay 29 is energized by the output of amplifier A to close the shunt circuit by closing contacts 60 and thus actuate the indicator 6|. Relay 29 will be energized .when the detector mechanism passes over the rail joint for the reason described above, namely, that the rail joint distortsthe magnetic field for a considerable distance and such distortion is picked up by the detector coils 20, is amplified by amplifier A and therefore energizes one or more of the output relays 29, 30, 3|. The relays 38 and 3| do not energize pen relays 34 and 35 when the mechanism passes over the rail joint because the circuit through relays 34 and 35 is broken at. 41, but the relay 29 does close the shunt circuit through the indicator 8| ifthe detector mechanism is operated. Should there be some fault in the detector mechanism anywhere between the induction coils 20 and the output relays 29, 39 and 3| it will at once become apparent because of the failure of signal 5| to be operated when the joint pen indicates that the mechanism is over a joint.

In accordance with the provisions of the patent statutes, I have herein described the prlncipie and operation of my invention, togetherwith the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatusshown is only illustrative and that the invention can be carditioned to be operated and the other of said indicating means is normally conditioned not to be operated, means actuated by the rail joint, a rail joint indicator, means whereby said rail joint indicator is actuated by said rail-joint-actuated means, means whereby said rail-joint-actuated means cpnditions said first indicating means not to be operated when said responsive means passes over a rail joint, and means whereby said second indicating means is conditioned to be operated when saidrail joint indicator is actuated.

2. In a rafl flaw detector mechanism, means responsive to fiaws, electrically operated indicating means, means whereby said indicating means is actuated by said responsive means, means actuated by the rail joint, a second electrically operated indicating means, means whereby said second indicating means is actuated by said railjoint-actuated means, an auxiliary electrically operated indicating means adapted to be. conditioned to be operated and conditioned not to be operated, means whereby said auxiliary indicating means is actuated by said responsive means,

- means whereby said rail-joint-actuated means conditions said first indicating means not to be operated when said responsive means passes over a rail joint, and means whereby said auxiliary indicating means is conditioned to be operated and conditioned not to be operated when said second indicating means is conditioned to be operated and conditioned not to be operated.

,3. In a rail flaw detector mechanism, means responsive to flaws, a plurality of electromagnetic relays actuated by said responsive means, a plu rality of indicating circuits, means whereby said circuits are controlled by said respective relays,

means for normally maintaining one oi said circuits in condition to be operated and the other of said circuits in condition not to be operated, and means whereby said first circuit is conditioned not to be operated and said second circult is conditioned to be operated when said responsive means passes over a rail joint:

4. In a rail fiaw detector mechanism, means responsive tofiaws, a plurality oi'"electromagnetic relays responsive to currents of varying magnitudes actuated by saidresponsive means,

responsive to relatively smaller currents con-- trols th other of said circuits, means for normally taining said first circuit in condition to be roperated and said second circuit in operated and said second circuit conditioned to be operated when said responsive means passes over a rail joint.

HARCOURT'C. DRAKE. 

